US 6982105 B2
A container assembly includes a container body formed of a thermoplastic material having an inner surface, an outer surface, and at least one corner having a reinforcement molded to the outer surface of the corner. The reinforcement has a peripheral edge, which is partially embedded in the outer surface of the container body. A method of making a container assembly comprises the step of molding a container body over a portion of a reinforcement. A reinforcement having a peripheral edge is disposed in a mold. A fluid thermoplastic material is disposed into the mold. The thermoplastic material is then molded over the inner surface of the mold and the peripheral edge of the reinforcement thereby forming the container body. The thermoplastic material contacts the peripheral edge and melts or softens the edge. A peripheral edge is then brought into engagement with the container body to provide a secure seal between the reinforcement and the container body.
1. A container body formed of a thermoplastic material having at least three sides with an inner surface, an outer surface, and at least one corner joining said three sides, a reinforcement of thermoplastic material disposed over said outer surface of said three sides of said corner, said reinforcement having a bottom surface and a top surface tapering to a peripheral pointed edge extending completely about said corner reinforcement, said thermoplastic material of said container body being disposed over said pointed edge to engage said tapered bottom and top surfaces completely about said peripheral edge for mechanically locking said reinforcement to said container body on all three sides thereof while exposing said top surface of said reinforcement.
2. A container assembly as set forth in
3. A container assembly as set forth in
4. A container assembly as set forth in
This application is a divisional of application Ser. No.09/079,726 filed on May 15, 1998 and now U.S. Pat. No. 6,294,127.
The subject invention generally relates to marine fuel tank assemblies and, more specifically to a blow-molded fuel tank assembly having reinforced corners and a method of making same. The method includes the step of molding reinforcements over a portion of a plastic fuel tank body.
Traditionally, plastic containers, such as fuel tanks, have been molded by a variety of techniques such as roto-molding and blow-molding. Historically, blow-molded fuel tanks have been disfavored since their corners are inherently thin. The thin corners leads to inherent weaknesses in the fuel tanks. Because fuel tanks must meet stringent governmental standards for both permeation and fire resistance, the prior art blow-molded tanks have been disfavored due to their proclivity towards permeation of fuel and decreased resistance to fire.
The prior art has not successfully addressed the problems set forth above for blow-molded fuel tanks. Thus, there has been a need for an improved blow-molded plastic container assembly which provides increased strength, low permeability, and increased fire resistance. There has also been a need for an improved blow-molding method of manufacturing these container assemblies.
The improved storage tank assembly of the present invention provides a blow-molded fluid sealed tank assembly without weakened corners which are typical in blow-molded plastic fuel tanks. The container assembly includes a plastic container body and at least one corner reinforcement. The reinforcement is molded over an outer surface of at least one corner of the container body. The reinforcement includes a peripheral edge which is partially embedded in the outer surface of the container body. The peripheral edge is also partially deformed and becomes partially cohesive with the outer surface of the container body providing locking engagement between the reinforcement and the container body.
In a method according to the present invention, a reinforcement is molded over the corner of a plastic container body leaving a portion of the reinforcement partially embedded in the molded container body. A mold is provided having an inner surface and an orifice, wherein the inner surface of the mold defines an outer surface of the container body. A reinforcement is disposed in the mold orifice with the portion of the reinforcement to be embedded into the container body positioned in the mold. The reinforcement also includes at least one peripheral edge which is partially embedded in the container body. A fluid thermoplastic material is introduced into the mold and forced against the inner surface of the mold and the peripheral edge of the reinforcement. The fluid thermoplastic material softens or partially melts the peripheral edge of the reinforcement. The peripheral edge is partially deformed forming a locking engagement between the container body and the reinforcement. The thermoplastic material comprising the container body and the thermoplastic material comprising the reinforcement can also cohesively bond together providing a secure seal between the container body and the reinforcement. Thus, sufficient thickness can be obtained at the corners without using greater amounts of plastic in the blow-mold process.
In the preferred embodiment, a blow-molded process is used to mold the container assembly. In this process, a fluid parison of thermoplastic material is introduced into the mold and a pressurized gas charge is introduced into the parison expanding the parison and confirming the parison to the inner surface of the mold. The thermoplastic reinforcement is preferably made by injection molding utilizing the same thermoplastic material as is used to form the container body.
The ability to produce parts with good material thickness in corners without making the balance of the part much too thick just to improve corners.
Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
The tank assembly 20 also includes a plurality of fixtures 26, 28, 30. Fixtures 26, 28, 30, are pre-fabricated pieces and comprise, for example, an injection molded thermoplastic material. Fixtures 26, 28, 30 preferably comprise a high density polyethylene thermoplastic material. For reasons set forth below, the container body 22 and fixtures 26, 28, 30 preferably are made from the same thermoplastic material. However, fixtures 26, 28, 30 will be thicker than the material container body 22. Typically, fixtures 26, 28, 30 will have a general thickness of approximately 4 to 7 millimeters. Fixtures 26, 28, 30 can each have a portion embedded in the container body 22, as described below. Each fixture 26, 28, 30 provides an opening into the interior 24 of the tank assembly 20. Each fixture has a cap associated therewith which seals the interior 24 to retain a fluid in the interior 24 of the container assembly 20.
The tank assembly 20 illustrated in
As shown in
The fixtures 26, 28, 30 are embedded in the plastic container body 22. This is shown and described in greater detail in co-pending application U.S. Ser. No. 08/704,130, assigned to the assignee of the present invention, and incorporated herein by reference.
Referring specifically to
The peripheral edge 44 of the corner reinforcement 40 can also become partially cohesive with the outer surface 23 of the tank body 22. That is, if compatible thermoplastic materials are utilized for both the corner reinforcement 40 and the tank body 22, the materials comprising the respective parts can form a cohesive bond therebetween. Additionally, the peripheral edge 44 of the reinforcement 40 can be partially deformed by the hot thermoplastic material comprising the tank body 22 and can thus provide locking engagement between the reinforcement 40 and the container body 22. That is, the deformed peripheral edge 44 allows for a mechanical lock to be formed between the deformed peripheral edge 44 having the material comprising the tank body 22 disposed thereover.
As shown in
Springs 100 disposed in bores 102 laterally bias the receiver 90 within the aperture 92. When the pin 42 of the corner reinforcement 40 is disposed within the bore 96 of the receiver 90, the springs 100 provide a lateral force on the receiver 90 to force the corner reinforcement 40 into engagement with the inner surface 84 of the mold 80. This mechanism insures that the corner reinforcement 40 will be maintained in its proper position during the molding operation and to allow controlled movement of the corner reinforcement 40 due to molding forces and thermodynamic effects such as expansion and contraction of the materials disposed within the mold 80. A keeper plate 106 disposed adjacent to the base portion 98 and the recess 104 retains the indexing mechanism within the mold 80.
As discussed above, a vent hole 58 can be disposed in the corner reinforcement 54. With reference to
In the process of the present invention, a hot fluid thermoplastic material is simultaneously disposed over both the inner surface 84 of the mold 80 and the peripheral edge 44, 52 of the corner reinforcement 40, 54. This step can be performed, for example, by any plastic molding method which is well known in the art. The preferred plastic molding method is blow-molding. In this process, a molten parison of fluid thermoplastic material may be disposed in the interior 81 of the mold 80. A pressurized gas, such as air, is then blown into the parison in the mold 80, thereby expanding the parison and conforming the parison to the inner surface 84 of the mold 80. The hot fluid thermoplastic material contacts the peripheral edge 44, 52 of the corner insert 40, 54 and can begin to soften or even melt at least a portion of the peripheral edge 44, 52.
The fluid thermoplastic material cools and hardens forming the container body 22. As the fluid thermoplastic material cools, limited shrinkage of the thermoplastic material can occur, drawing the peripheral edge 44, 52 and the container body 22 together. The peripheral edge 44, 52 can be deformed, thereby producing locking engagement with the container body 22. Additionally, as discussed above, cohesive bonding between the peripheral edge 44, 52 and the fluid plastic material comprising the container body 22 can also occur.
A preferred description of this invention has been disclosed; however, one of ordinary skill in the art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied in order to determine the true scope and content of this invention.
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